PROJECT SUMMARY Adolescents struggle with managing type 1 diabetes (T1D), with glycohemoglobin >7.5% in ~75% of patients, often coupled with coping difficulties, diminished quality of life and high risk of complications. Psychosocial and behavioral mechanisms are major influences on T1D outcomes, but current care is ill-equipped to address these issues. Growth in clinical populations of patients with T1D (and other endocrine disorders) outstrips the current and projected supply of pediatric endocrinologists. The premise of this application is that a model of T1D care that achieves health care force multiplication, while also addressing psychosocial barriers to self care more effectively, could improve these outcomes substantially. This application will support rigorous and reproducible development and testing of a Transdisciplinary Care (TC) model in which T1D is co-managed by an Advanced Practice Nurse, Dietitian and Psychology Postdoctoral Fellow who will see adolescents conjointly. TC team members will train one another in the principles and clinical practice of their respective professions and integrate evidence-based behavioral assessment and intervention methods into family- centered treatment plans. The proposed 3-year series of studies will address these specific aims: AIM 1. With methods used effectively in our ongoing DP3 study of parents of children <6 with T1D, we will engage separate ?crowds? of youth with T1D, parents, and HCPs in planning/refining a feasible, safe, acceptable and efficacious TC model for adolescents with T1D. These efforts should yield a TC model that meets the needs of key stakeholder groups, ensuring that it is safe, feasible, acceptable and reproducible. AIM 2. In Years 2-3, 150 families of adolescents treated for T1D at Nemours practices in the Delaware Valley or Florida will participate in a rigorous Randomized Controlled Trial (RCT). The RCT will compare effects of Usual Care (UC) with those of Trans-Disciplinary Care delivered in Face to Face clinic visits (TC-FF) or via Telehealth (TC-TH) on glycemic control, treatment adherence, health care use, T1D-related distress, quality of life, and treatment satisfaction. The proposed trial will yield substantial information that could justify and inform a definitive future test of this model, and determine if Telehealth or Face to Face delivery of TC would be better justified for evaluation in a future trial. AIM 3. Qualitative interviews of adolescents, parents, health care providers and third party payers at key time points during and after the RCT will identify possible mediators or moderators of TC efficacy and guide refinements to the TC model. These analyses will inform improvements to the TC model to further enhance its feasibility, acceptability, reproducibility, and efficacy, justifying a future multi-site trial.